Step 1 - Briefly remembering how to name hydrocarbons
To name a hydrocarbon we must follow some steps:
a) count the number of carbons: this will give you the correct prefix (met, et, prop, ...)
b) check if there are any double or triple bonds: this will give you the infix (-an-, -en-, -in-, ...)
c) check the organic function: this will give you the sufix (-e, -ol, -one, ...)
Step 2 - Naming each hydrocarbon
a) The given structure is:
number of carbons: 5 (pent-)
double/triple bonds: none (-an-)
organic function: alcane (-e)
Compound's name: pentane
b) The given structure is:
Number of carbons: 3 (prop-)
Double/triple bonds: yes, between carbons 1 and 2 (-en-)
Organic function: alkene (-e)
Compound's name: propene
c) The given structure is:
Number of carbons: 3 (prop-)
Double/triple bonds: yes, between carbons 1 and 2 (-in-)
Organic function: alkine (-e)
Compound's name: propine
d) The given structure is:
Number of carbons: four in the principal chain (but-), one in the ramification (methyl)
Douple/triple bonds: no (-an-)
Organic function: alkane (-e)
position of the ramification: attached to carbon 2
Compound's name: 2-methyl-butane